, Volume 48, Issue 2, pp 233–245

Unbiased estimators of ability parameters, of their variance, and of their parallel-forms reliability

  • Frederic M. Lord

DOI: 10.1007/BF02294018

Cite this article as:
Lord, F.M. Psychometrika (1983) 48: 233. doi:10.1007/BF02294018


Given known item parameters, unbiased estimators are derived i) for an examinee's ability parameterθ and for his proportion-correct true scoreς, ii) for the variances ofθ andς across examinees in the group tested, and iii) for the parallel-forms reliability of the maximum likelihood estimator\(\hat \theta\).

Key words

item response theory true score latent trait theory maximum likelihood 

Copyright information

© The Psychometric society 1983

Authors and Affiliations

  • Frederic M. Lord
    • 1
  1. 1.Educational Testing ServicePrinceton

Personalised recommendations